Torlon 7130 is in particular troublesome, with the carbon-fiber filling. On the other hand, it is a fantastically stiff plastic for uses where one needs that. Carbide works "OK" as noted (as I found), but diamond is no doubt better by a long shot. The bearing grade material is a similar issue, just on a different scale, based on the different type of carbon filling.
Many plastics do absorb water; nylon is a classic example of a resin that machines and performs most optimally when it has something like 7-10% of its mass consisting of water. And for those applications where fits are critical, relative humidity can have a big (read: problematic) effect. I made some hard disk test mount hubs for inspection equipment some years back from Torlon; they fit very nicely to +0/- .0005" tolerance when tested here in AZ., home of dry heat, but when shipped on equipment to Pacific Rim mfg facilities, the disks no longer fit due to size change from humidity absorption. Lesson learned.
